Blood treatment apparatus and similar medical devices comprise an extracorporeal circuit, provided with at least one blood treatment or blood processing unit, one tube, connecting a blood removal zone to said unit, and a second tube, extending downstream of the treatment or processing unit towards a blood return zone to the patient or towards a blood/blood components collection zone. Blood is moved from the patient or donor to the treatment or processing unit via pumps or other actuators controlled by the machine.
In case the machine is for instance a hemodialysis apparatus, then for achieving the required treatment of blood, an adequately prepared dialysis liquid shall be sent to the treatment unit, water removal through the treatment unit membrane as well other machine parameters shall be controlled. Depending upon the type of hemodialysis machine and upon the type of treatment, a user can have the possibility to set a number of parameters in order to impose a specific prescription to a patient, such as for instance: flow rates of the various liquids, temperatures and conductivity of the liquids, concentration of the liquids used during treatment, flow rates of any anticoagulants used and delivered during treatment, pressures in the fluid conduits, net liquid removal rates of plasma water from whole blood and so on.
It is therefore evident that users (the patient himself, a physician, a nurse) have normally a plurality of parameters to set before or even during the process performed by the medical apparatus. Moreover it is clear that easy and safe, data entry as well as data storage and transmission are particularly important in machines as blood treatment machines or blood processing apparatus where the process executed by the machine acts on a patient or donor blood. Particularly in case of treatment of blood of patients suffering from kidney failure the patient is constantly connected to the machine with the serious risk that any failure in entering or in actuating a proper prescription could have negative impacts on the treatment delivery and on patient's health.
In this situation several technical solutions have been developed in the past in order to render easy and reliable data entry in blood treatment or blood processing apparatus. A first known method for entering data in a dialysis machine is described in U.S. Pat. No. 5,247,434. This method comprises the following steps:
(a) providing a touch screen interface with an indicium thereon corresponding to a treatment parameter;
(b) touching the indicium;
(c) in response to said touching, invoking a data entry pad on a region of the touch screen;
(d) entering a parametric value corresponding to the treatment parameter by touching one or more buttons of the data entry pad;
(e) touching a first region of the data entry pad to signal entry of the parametric value;
(f) displaying on the touch screen a button soliciting verification of the newly entered parametric value;
(g) touching the button soliciting verification; and
(h) in response to steps (b)-(g), causing the parametric value corresponding to the treatment parameter to be changed.
In other words before really implementing the change the user is solicited to verify the newly entered parameter and press a button confirming the change.
The same patent also discloses a method for entering variable parameters, i.e. parameters that can vary in the course of time during treatment.
More in detail U.S. Pat. No. 5,247,434 shows a method of programming a time-varying parameter comprising the steps:
(a) providing a touch screen interface;
(b) displaying on the touch screen first and second axes, the first axis corresponding to the time-varying parameter, the second axis corresponding to time;
(c) touching the touch screen at a plurality of points to define points on a parameter-versus-time curve;
(d) presenting on the touch screen a series of bars corresponding to said curve;
(e) selecting one of said bars for alteration;
(f) displaying on the screen a numeric parameter corresponding to the selected bar;
(g) touching the screen at first or second locations to increase or decrease, respectively, the displayed numeric parameter and thereby alter the value of the numeric parameter to which the selected bar corresponds;
(h) touching the screen at a third location to signify completion of steps (b)-(g); and
(i) storing data corresponding to the bars in a memory to which the process-control system can refer in changing the time-varying parameter with time.
From document U.S. Pat. No. 5,326,476 is known a further method for entering a time variable parameter, ultrafiltration in particular, in a hemodialysis machine, having a programmable memory and having ultrafiltration capability, so as to enable the machine to perform ultrafiltration of fluid from a patient according to a time-variable ultrafiltration profile. The method disclosed in U.S. Pat. No. 5,326,476 comprises the following steps:                (a) entering into the programmable memory a prescribed time for dialysis;        (b) entering into the programmable memory a target ultrafiltration volume of fluid to be removed from the patient;        (c) entering into the programmable memory a proposed ultrafiltration profile being representable as a plot of coordinates on an ultrafiltration rate axis and a time axis and defining a profile ultrafiltration volume; and        (d) shifting the proposed ultrafiltration profile along the ultrafiltration rate axis to the degree necessary to make the profile ultrafiltration volume equal to the target ultrafiltration volume, so as to allow the hemodialysis machine to achieve, while ultrafiltrating the fluid according to the shifted ultrafiltration profile, the entered target ultrafiltration volume within the entered prescribed time.        
This method allows the user to enter a profile curve and to move the ultrafiltration profile along the ordinates so as to achieve the desired integral value in the desired time frame.
A further system for a dialysis machine is known from document U.S. Pat. No. 5,788,851 and comprises:                a touch screen displaying messages and information and permitting to select a parametric value pertinent to operation of said machine or pertinent to a treatment by said machine,        one hard key off of said touch screen, said touch screen prompting a user to press said hard key to signify that the selection of the parametric value has been completed;        a control system having a host and a safety processing unit, wherein pressing of said hard key causes transfer of information relating to the selected parametric value from the host processing unit to the safety processing unit which is then checking said selected parametric value to confirm that said parametric value meets validation or safety criteria for a patient connected to said machine.        
The above system is therefore using two processing units in order to insure that unsafe parameters values are entered into the machine.
It is also known from U.S. Pat. No. 6,811,707 using a dialysis machine wherein after entry of a value for a parameter the value is stored in at least two different memory locations connected to corresponding separate main control units. At predetermined intervals of time, one of the units sends the dialysis treatment parameters values stored in its memory to the other unit. The values are then compared and an alarm signal generated if the values of the same parameters in the two memories of the two units do not coincide with each other.